Different types of planting material

The success of growth after planting depends very much on the planting material and its root system. In order to plant trees we mention the 5 most important options of planting material:

1. Seed (from F1 hybrids, from variable populations, etc.)
2. One year old saplings on plugs (from seed, from cuttings, from tissue culture, etc.)
3. Two year old saplings on pots
4. One year old saplings with bare roots
5. Two or more year old sapling with bare roots

Option 1

After germinating the seed starts with the development of the radicle. This first root has a huge power to enter the soil and is even strong enough to break rocks, through breaking the sometimes only with a microscope visible cracks of rocks. The pressure that a radicle is able to develop is more than 50 bar (725 psi). This is a pressure of 50 kilo’s per cm²! That’s why trees are able to break and grow on rocks. As soon as the plant has enough water via the radicle to grow and to evaporate, the shoot develops and assimilation starts. Now the plant develops its root system under the surface and its stem-branch-leave system above the surface. During the development of the system the first roots – the primary roots with length development - have the strongest power to grow deep. Its instrument to do this is the apical meristem that is the cause of lengthening. The best way to plant in dry soils or on rocks is to plant seeds.

Option 2

In general saplings from cuttings or seed are first planted into a little space using plug and afterwards in a more space using bigger pot.

Plugs from cutting

After the cutting has been planted, its root system starts to develop. If the rooting is successful the cutting in general develops more than one root. These roots are called primary roots too. If we take these saplings from the plug without damaging the primary roots, these primary roots will have a lot of power to grow into dry soil or rocks, but they have less power than a radicle from a seed.

Plugs from a seed

The seed will develop a radicle in the plug with the same power to break rocks as when sown directly into the soil.

The less positive side of using a plug

With plugs and pots we have two negative characteristics:

1. Once the root starts to grow rounded instead of vertically downwards they will have a lot of difficulty to grow vertically after planting. Many times they won’t. So if you have a rounded root in the plug or pot, this sapling is not useful for dry soils or rocks. It will fail. You can prevent roots growing rounded by choosing plugs or pots with a design that stimulates roots to grow vertically downwards. The first rule for a good plug or pot is that its design cannot be rounded on the outside. Choose a reversed pyramid model, a square one or a model where the outside is unequal. Look at the images for an example of a well designed plug.
2. Once the radicle grows well and vertical, it will come to the bottom of the plug. If at that moment the plug is not planted, the radicle will stop growing downwards and loose a part of the active apical meristem cells. The radicle will split in many small primary roots who have less power to break into dry soil or rocks. Besides this the radicle will start to grow up again and then start to grow rounded. Once doing this, it will never change this habit again. This means that if you plant a plug with a rounded radicle root, then this root will never turn downwards and start growing into the dry soil or into rocks. If you are lucky some of the radicles will develop a new radicle root growing downwards, but the majority will not. This is why planting trees on rocks or trees in dry or eroded areas who are pre-rooted in plugs will mostly fail if they do not get help through irrigation. In 2007 I planted as an experiment saplings of Metasequoia glyptostroboides. These were one year old trees multiplied through cutlings and had rounded radicles in the plugs. I took them out during December 2009, two years after planting. On the images you can see that most of the radicles did not recover and less than 20% of the survived saplings had developed a new radicle root again. Over 50% of this trial that was planted on a dry sandy soil in Holland – which is a country with sufficient rain – died. You can see this bad phenomenon of non-recovered rounded radicles on the images. So if you want to plant trees in deserts, eroded areas or on rocks, then use seeds or use the method as described in the following chapter “Future”.

As a result of these two less positive characteristics, plugs or pots are the second best way to plant trees or bushes in dry soils or on rocks.

Future

With the waterboxx we can plant every day of the year. For explanation of what this means, visit this link. The negative aspect of sowing seed directly in the waterboxx on the final planting place is that it is difficult to estimate the germination percentage after sowing. In order to reduce the risk of non-germination we have developed the twinplant idea. By sowing two seeds, the risk of failure is lower. In the future however I expect another development that will really improve our results. This development is a copy of a normal practice in the Dutch vegetable and flower industry: there are specialized young plant producers who supply their clients following the J.I.T. (=just in time) principle. Suppose a chrysanthemum flower grower knows that he wants to plant on June 17. The young plant producer knows that producing a cutting takes him for instance 27 days. He then cuts the cuttings and roots them on May 21. In this way the cutting is well rooted and in good condition on the delivery date.

This development will start to be used in the tree industry too. Once we start to plant trees according to planting schedules with the waterboxx, we know the plant date in advance. Within a few years from now tree sapling producers will know exactly how many days the sapling needs to produce a radicle to the bottom of the plug. Suppose this is 45 days for a Pinus ponderosa. Then the sapling producer will sow the Pinus ponderosa saplings 45 days before the planting date in his plugs and deliver them to the final planting place JIT, which means that the radicle is not divided into primary roots that are weaker to enter into dry soil or rocks. The advantages of sowing in advance using the JIT principle are that we keep the radicle intact and we have less problems caused by germination failure. If we have 80% germination success rate, then we plant the 80% of the plugs, two per waterboxx, and we are sure that we have two saplings per box. After the first year we cut the weakest of the two and have a positive mass selection that will give us better Return on Investment as we are using the strongest individuals.

View the images in order to understand how perfect plants in the future look like - produced by www.tenax-plugs-seeds.nl in Holland

Option 3

The cutting can be planted immediately on the definitive pot in which it will be sold and the root system will then be as written under Option 2. But many times the trees planted on pots are taken from a plug. If during this replanting from the plug into the pot the primary roots are damaged, then re-growth of these roots will happen. But each root that re-grows will produce a few primary roots that are weaker than the original. These roots have less power to enter dry soils or rocks. The third best way to plant in dry soils or on rocks is to plant trees grown on pots.

Option 4 and 5

With bare roots the root system is heavily damaged while taking them from the soil in order to re-plant them to their final place. In general the primary roots are destroyed and the tree is not qualified to be planted in dry soils or on rocks. Trees planted with bare roots will not survive in a dry soil or on rocks without heavy irrigation.

Radicle or Pen root? Conclusion

You now understand that the basic thing to have good success in deserts or on rocks, is keeping the radicle or pen root intact. Some trees have a better pen root than others. Some species have a divided root system as a characteristic and other species have a specific pen root that stays intact all the time. For planting in dry soils or on rocks we prefer tree species with this specific "pen root". This primary root is able to penetrate very dry soils or rocks deeply. Some roots have been found to over 60 meter deep.

For further information about roots and how deep they can grow, look at this interesting article on Wikipedia.

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Specifications of planting material